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Lesions posterior to the odontoid process pose a surgical challenge. Posterolateral approaches to this region are considerably risky for the spinal cord. Transoral approaches are limited in terms of exposure and can also carry morbidity. We describe a focused endoscopic endonasal approach (EEA) for removing an osteochondroma located dorsal to the odontoid process. The surgical pearls and pitfalls using stepwise image-guided EEA cadaveric dissections are highlighted defining the importance of various craniocervical junction (CCJ) lines on imaging. EEA to CCJ can be offered, with lower morbidity than other approaches, even for lesions that extend posterior and caudal to the odontoid process. Radiologic predictors of exposure and intraoperative techniques to enhance endoscopic visualization are discussed.

Expanded endonasal endoscopic techniques allow us to treat several pathologies related to the odontoid process and craniocervical junction. Cases such as giant basilar invagination represent a surgical challenge. The authors provide technical nuances and describe how to complete an endoscopic endonasal odontoidectomy and release the craniocervical junction with the aim of restoring a correct sagittal balance in cases with giant basilar invagination. The study of cadaveric specimens adds clarifying dissections. Endonasal endoscopic odontoidectomy and craniocervical junction joint release allow the treatment of irreducible basilar invagination and restoration of better sagittal balance before posterior cervical occipitocervical fusion.

Early fixation of type II odontoid fractures has been shown to provide high rates of long-term stabilization and osteosynthesis.In this report, the authors present the case of a patient with a locked type II odontoid fracture treated by anterior screw fixation facilitated by closed transoral and posterior cervical manual reduction.While transoral intraoperative reduction of a partially displaced odontoid fracture has previously been described, the authors present the first case utilizing this technique in the treatment of a completely dislocated type II odontoid fracture.

Background. The management of odontoid fractures represents both a clinical and a technical challenge due to the singular anatomy and biomechanics of the region. At present there is still much controversy as far as any form of management (surgical vs. conservative) is concerned and in any case there is not sufficient evidence to support a standardized form of treatment. This study was designed to further evaluate safety and efficacy of anterior odontoid single-screw fixation and to better determine the usefulness of Image Guided Surgery Virtual Fluoroscopy in treating such cases assessing also its advantages over traditional fluoroscopy and CT-guided frameless stereotaxy in the upper cervical spine surgery. Methods. This was a retrospective review of ten patients presented during a short period of 18 months with acute traumatic Type II odontoid fractures. Nine underwent fixation within a mean of 3 days after injury, whereas a patient had to be operated upon on the 22nd day due to poor alignment with conservative treatment and ongoing instability. All patients postoperatively were fitted in a collar and then followed-up with serial clinical and radiographic examinations. Findings. Radiological signs of fusion were seen in 10 cases (100%) (mean follow-up: 16 months). No complications occurred during the surgical procedure, nor were any instrumentation failures recorded; all patients remained neurologically intact. Conclusions. We believe that anterior odontoid screw fixation using Image Guided Surgery virtual fluoroscopy is a safe, effective, less time consuming and low x-ray exposure technique and we recommend this as the preferred treatment method for acute Type II odontoid fractures. Moreover, the use of image guided technology affords more precision, confidence and safety enabling the surgeon to approach the upper cervical spine in an easier and faster way.

Background. Reducible atlanto-axial dislocation (AAD) may cause severe motor and respiratory compromise due to recurrent spinal cord and/or brain stem impingement. To the best of the authors' knowledge, this is the first study concentrating on the classification, the protocol of the surgical management and the outcome of congenital, reducible AAD. Methods. 109 patients with congenital, reducible AAD underwent posterior stabilization. Their preoperative disability was graded as: I (n = 11, 10.09%) no functional disability (a history of minor trauma led to quadriparesis that subsequently improved); II (n = 31, 28.44%) independent for activities of daily living with minor disability; III (n = 42, 38.53%) partially dependent on others for their daily needs; and, IV (n = 25, 22.93%) totally dependent. They were classified into 4 groups depending upon their association with: a normal odontoid and posterior arch of atlas (n = 27); a dysplastic odontoid and normal posterior arch (n = 25); an assimilated posterior arch (n = 49); and, Arnold Chiari malformation type I (n = 8). Nine patients with a dysplastic odontoid had a hypermobile AAD with an unrestricted backward and forward movement of the axis relative to the atlas in flexion as well as in extension of the neck, respectively. The surgical procedures included Brooks' (n = 12) or modified Brooks' Cl-2 fusion (n = 39); Goel's C1-2 fusion (3); Ransford's contoured rod fusion (n = 7); Jain's occipitocervical fusion (n = 47); and, transoral decompression and Jain's occipitocervical fusion (n = 1). There were 6 peri-operative mortalities in the series. Findings. At follow-up (ranging from 3 months to 6 years; n = 86), 64 patients had shown improvement by one grade or more; 8 patients, who had a history of transient quadriparesis but were without neurological deficits at presentation, remained in grade I; 11 had achieved stabilization of neurological functions; while 3 had deteriorated despite adequate radiological reduction of AAD and fusion of the construct. A follow-up of 6 months or more was available in 79 of these 86 patients, in whom a dynamic intrathecal CT scan showed a good osseous union. Interpretation. The patients with congenital reducible AAD, depending on their surgical management, may be classified into four groups. Some patients with a dysplastic odontoid have a hypermobile AAD and require special care during intubation, positioning and stabilization. An assimilated posterior arch is often associated with asymmetrical lateral occipito-C1-C2 joint synostosis rendering transarticular screw placement difficult. The various causes of failure of constructs are discussed.

Background. Due to the paucity of existing data with regard to surgical fusion of upper cervical spine instabilities in the paediatric population, we feel encouraged to report the results of our own series to provide additional information to the available body of literature. Methods, Since 1991 N = 11 children underwent a total of N = 13 surgical procedures for N = 8 posttraumatic, N = 2 congenital and N = I postinfectious instabilities at a mean age of 10 years (range: 3-16 years). Transoral odontectomies, ventral odontoid screw-fixations, dorsal wiring or -clamping and transarticular screw-fixations were performed for stabilization and iliac crest bone graft used for fusion. Pain scores, neurological status and radiological results were documented at regular intervals (mean follow-up: 25.4 months). Results. Stable fusion was achieved in all patients as documented on flexion/extension films and tomographies. At the latest follow-up N = 2 patients had improved and N = 9 were equal to their preoperative neurological status. Pain scores were improved in N = 9 patients. N = 2 children developed bystander-fusion after C0/2 wiring. N = 3 peri-operative complications occurred as transient neurological deteriorations. In one case this resulted from the resection of a lower brainstem tumour prior to the stabilization procedure. One was attributed to sublaminar wiring in the case of an os odontoideum and one occurred due to slippage of the halo orthosis after transoral odontectomy before definitive dorsal stabilization was carried out. Interpretation. In accordance with the recent literature, we argue for the application of modern screw fixations and treatment algorithms as established for adults in upper cervical spine instabilities of older children. Techniques and indications remain problematic for those younger than 6 years and may have to be individualized in congenital instabilities.

Anteriorly located lesions at the craniocervical junction (CCJ) require careful surgical planning to avoid neuraxis retraction. Several different routes have been described in the search for the most appropriate yet least invasive approach. However, most of these far-lateral posterior approaches are specifically tailored for non-osseous intradural tumours or chordomas with cephalad extension. We introduce an approach that allows for better access to laterally extending osseous tumours originating from the second cervical vertebra. Using this approach, the lesion is manipulated from a strictly lateral direction parallel to a plane through the articular pillar of the CCJ and the odontoid process, and the C1- and C2-laminae are spared for posterior fixation.The application of this approach is demonstrated in detail by an illustrative case of a chordoma originating from C2 that presented with intradural mass effect, considerable bone destruction, far-lateral extension to the right, and vertebral artery involvement.The described approach gave ample access for total tumour resection. It allowed for safe control and displacement of the vertebral artery, spinal cord decompression, C2-corpectomy across the midline, and anterolateral bone reconstruction. No C1- or C2-hemilaminectomy was needed, and these bone elements could be used for posterior fixation (the patient presented in this study was referred to our institution after posterior fixation from the occiput to C3 had already been performed elsewhere). No intra-operative or postoperative complications occurred. At the 6-month follow-up, the patient was fully ambulatory with no neurological deficit.The described lateral transfacetal route is the method of choice for operating on laterally extending osseous tumours originating from the second cervical vertebra.

A small subset of patients with adult Chiari I malformation without basilar invagination (BI) and instability show ventral cervicomedullary distortion/compression and have symptoms pertaining to that. The cause of this ventral compression remains speculative. Additionally, it is unclear if these patients would require ventral decompression with posterior fusion or only posterior decompression would suffice. Sixteen adult patients with Chiari I malformation with significant ventral cervicomedullary compression, in the absence of BI, were included in the study. Atlantoaxial dislocation (AAD) was excluded in these patients by flexion-extension craniovertebral junction X-rays and computed tomography (CT). Their clinical profile, especially symptoms pertaining to cervicomedullary compression, i.e. dysphagia, dysarthria and spasticity, were graded. The ventral cervicomedullary compression (VCMC) was quantified using pBC2 (maximum perpendicular distance to the basion-infero posterior point of the C2 body) on sagittal magnetic resonance imaging (MRI) and only those patients with pBC2 ≥9 mm were included. Furthermore, retroversion of dens and retro odonotid tissue thickness was calculated in each patient. Fifteen patients underwent posterior decompression alone and one refused surgery. Follow-up was done every 3 months. Repeat MRI was done at 1 year following surgery to look for pBC2. The mean pBC2 was 11 ± 0.2 mm. Retroversion of dens was responsible for VCMC in three patients and periodontoid crown in 13. There was no correlation between the tonsillar descent, age and the pBC2. All patients improved in symptoms of cervicomedullary compression following surgery. One patient worsened 6 months after initial improvement. The pBC2 did not change, as seen on follow-up MRI done in five patients. VCMC in adult patients with Chiari I malformation in the absence of BI and/or AAD is due to periodontoid tissue (crown) or retroverted dens. Though a long-term study is required, it appears that all patients with Chiari I malformation, irrespective of the VCMC, can be given a chance with posterior decompression alone. Transoral decompression with posterior fusion may be required in a small subset of patients who fail to improve or worsen following posterior decompression only.

We report an extremely rare case of a 22-year-old man with an asymptomatic osteochondroma of the dens of C2 vertebra accidentally found during a brain CT scan examination.

The authors report on the development of myelopathy in a case of hypoplastic upper cervical spine with atlanto-axial instability. Its surgical treatment with transarticular screw fixation and interlaminar fusion is outlined.

In order to develop an endoscopic endonasal approach to the ventral cranio-cervical junction and odontoid process under the concept of a minimally invasive surgical strategy, a cadaver study was performed.Sixteen artery-injected adult head specimens were used. Endonasal endoscopic approach was made through one- or two-nostril routes following the Jho's endonasal paraseptal technique. Rod-lens endoscopes, which were 2.7 or 4 mm in diameter, 18 cm in length with 0-, 30-, and 70-degree lenses, were used.Surgical landmarks leading to the craniocervical junction were the inferior margin of the middle turbinate, nasopharynx and Eustachian tube. The nasopharynx was readily identified following the inferior margin of the middle turbinate. The line drawn between the Eustachian tubes indicated the juncture between the clivus and atlas. With a midline mucosal incision, the ventral cranio-cervical junction was exposed. Odontoid resection was performed with removal of the anterior arch of the atlas. Clival resection can be performed as much rostral as required. Maneuverability of the surgical instruments was better with a two-nostril technique than with a one-nostril. Although the entire midline clivus was accessible rostrally, C-2 was the caudal limit through this endonasal route. A suturing device needed to be developed for mucosal or dural closure for live operations.This cadaver study demonstrates that an endoscopic endonasal approach to the ventral cranio-cervical junction and odontoid process can be a valid alternative to the conventional transoral approach.

We describe a new instrument and a percutaneous technique for closed anterior fixation of odontoid fracture. The instrument which we developed consists of a telescopic tube system. This new instrument and closed fixation technique was used in six cadavers with type II odontoid fractures and to two cadavers with an intact odontoid process. Each cadaver underwent satisfactory placement of the screw to the odontoid with this technique under biplanar scopy control. After this procedure, no serious injury was found in the parapharyngeal and neurovascular areas of the necks of the cadavers, in which anatomical dissection along the track of this instrument was performed. The instrumentation and the technique as a whole is seen as reliably applicable for odontoid fracture fixation. Also, we expect to reduce operating time and hospital costs because this system is simple, easily applicable and minimally invasive.

The most common injury to the odontoid process in children under the age of seven years is a fracture through the synchondrosis with or without anterior displacement of the odontoid process, but this is not the only type of fracture of the odontoid process in this age-group. Fractures above and below the synchondrosis and fractures with posterior displacement were described. Typical clinical features of these fractures are: (1) major and blunt trauma, (2) neck pain and resistance to active and passive head movements; and (3) no or only slight neurological deficits. Conservative treatment had excellent results in the majority of cases. Nevertheless, there are a few specific indications for surgery.

Direct fixation of odontoid fractures has the advantage of preserving rotation in the atlanto-axial motion segment. Early mobilisation of patients and minor intra-operative trauma increase the value of this technique. The original screw method of Nakanishi, Magerl, and Böhler, was improved by Knöringer who designed a double-threaded screw for direct fixation of dens axis fractures. He stated that double screwing is absolutely necessary in order to prevent rotation of fragments against each other. The purpose of the present study was to describe a new single screw for direct fixation of odontoid fractures, which is easy to place into the limited space of the dens axis and which offers enough rotational stability and sufficient compression of fracture fragments. The so-called hollow spreading screw system (HSS) consists of an outer hollow screw, a spreading insert, a toothed washer, an hexagonal nut, and a protective nut. Thirty-five patients with traumatic and arthritic odontoid fractures were treated using direct internal fixation with the HSS system. In 30 cases, there was a type-II-fracture, in 3 a shallow type-III-fracture, and in 2 a type-II-fracture with pseudarthrosis formation. Pre-operative neurological deficits were seen in 16 cases. No additional neurological deficits were caused by the surgical procedure. The bony fusion rate of fresh fractures in the presented series was 100%. With the HSS system, ca. 12% postoperative complications, such as slight reduction of head rotation or neck pain, were found. These results are virtually equal to the results of the double-screw technique. Since a relatively simple technical procedure is required for placement of the screw, the HSS system can be recommended in all cases of odontoid fractures suitable for direct anterior fixation.

Crowned dens syndrome is defined as an association of acute cervical pain and calcifications in the peri-odontoid space. The authors report one case of this rare localization of hydroxy-apatite rheumatism and review 12 similar cases in the literature. This disease affects only adult females. Patients present with inflammatory signs, can be treated with non-steroid anti-inflammatory drugs and recover without sequela. Calcium pyrophosphate dihydrate deposition can also lead to this syndrome. Other perioodontoid calcifications and ossifications, usually asymptomatic, appear only as a radiologically crowned dens.

The clinical, radiological and surgical findings of 56 patients with congenital malformations of the craniovertebral junction who underwent surgical intervention in the Department of Neurosurgery, Hacettepe University Medical School were reviewed. The anomalies were classified according to their embryonic origin. Forty-two cases of the series were major abnormalities formed by the combination of more than one germ layer.

A case of platybasia associated with syringomyelia is presented where the syrinx regressed nearly completely after transoral resection of the dens. This course seems to be of considerable interest because it is hardly explainable by the common theories which try to elucidate the pathogenesis of syringomyelic cysts.

A 72-year-old woman with diabetes mellitus presented with a progressive two-week history of neck pain and right hemiparesis. On admission to our hospital, the patient was afebrile but showed slight neck stiffness. Results of the laboratory examinations were normal except for a high fasting blood sugar of 188 mg/dl and two-plus glycosuria. Radiographs showed basilar impression and assimilation of the atlas Fig. 1a). MRI revealed compression of the upper cervical cord by the invaginated odontoid process and a mass lesion at the retro-odontoid space (Fig. 1b, c, d). Right hemiparesis was progressive after admission. So treatment with steroid and insulin was started and the right hemiparesis greatly improved. The patient then underwent transoral surgery two weeks after admission. The anterior arch of the axis was removed and the odontoid process was drilled out. The tip of the odontoid process was eroded and osteomyelitis was diagnosed. However, bacterial cultures of the resected specimens were negative for aerobic and anaerobic bacilli including Mycobacterium tuberculosis. Empirical antibiotic therapy was initiated with cefazolin 4g iv per day. Her neurological status was unchanged immediately after surgery and remained stable until the second postoperative day. Thereafter, the patient deteriorated rapidly with right hemiparesis on the third postoperative day followed by tetraplegia and apnea developing over the next few hours. Emergecy CT suggested compression of the upper cervical cord by a combination of residual odontoid process, body of the axis, and epidural soft tissue material. Urgent transoral re-operation was done and residual odontoid process, and the body of the axis were drilled out. An epidural abscess was noted behind the odontoid process and this was also removed. Pulsatile dural protrusion was observed afterward. The patient subsequently underwent occipitocervical fixation with iliac bone from occiput to C4. Tetraplegia and apnea recovered slowly, but the right hemiparesis persisted.

Non-union of odontoid process fractures with displacement in old patients have been treated operatively with compact stable acrylic fixation. Immediate mobilization without external fixation was achieved.

The transclival-transcervical approach to lesions of the craniocervical junction is described. It gives reasonable access to the lower part of the clivus and to C1 and C2 for removal to tumours and stabilization of fractures and otherwise caused dislocations of this region. Because an opening of the pharynx can be avoided, reconstruction work can be done using bone graft or reinforced methyl-methacrylate without risk of infectious contamination. The results obtained in 6 cases are presented.